1. Field of the Invention
The present invention relates to a tray, and more particularly, to an apparatus for transferring a tray in an upright position that can sense an entrance and discharge of the tray.
2. Discussion of the Background
An electroluminescent display device, which is a type of flat panel display, can be categorized as an inorganic electroluminescent display device or an organic electroluminescent display device, depending upon the source material used to form an emission layer. An organic electroluminescent display device has certain advantages over the inorganic type. Specifically, an organic electroluminescent display device may be driven by low voltage, be lightweight, have a thin profile, a wide viewing angle and a short microsecond response time for displaying an image.
An organic electroluminescent (EL) device of an organic electroluminescent display device can consist of an anode, an organic material layer, and a cathode formed in layers on a substrate. The organic material layer includes an organic emitting layer, which emits light by combining holes with electrons. To efficiently transport holes and electrons to the organic emission layer to emit light, an electron injecting layer and an electron transport layer can be formed between the cathode and the organic emitting layer, and a hole injecting layer and a hole transport layer can be formed between the anode and the organic emitting layer. These additional layers can improve the emission efficiency of the organic EL device.
An organic electroluminescence device with the structure as described above can be produced by a physical vapor deposition method such as a vacuum deposition method, an ion plating method and sputtering or a chemical vapor deposition method using gas reaction. Of these methods, the vacuum deposition method is widely used. In the vacuum deposition method, carried out in a vacuum chamber, organic material is vaporized in a deposition source, and organic material vapor is ejected from the deposition source and deposited on the substrate.
As displays have become larger, the size of the substrate has also become larger. Thus, a deposition system has been developed in which a deposition source moves up and down inside a vacuum chamber and ejects organic material vapor to form an organic material layer on the larger substrate.
In this type of deposition system, the deposition source can be driven by a driving shaft rotating axially to move the deposition source up and down. While the deposition source moves up and down, the deposition source ejects organic material vapor formed by evaporating organic material.
As the substrate has become larger, a vertical alignment system for aligning the substrate and the mask while positioned upright state has been developed. A vertical alignment system would prevent a larger substrate from bending during the deposition process, thus providing a deposition of higher quality.
To position the substrate vertically, a substrate tray holder can be installed and reciprocated. A fixing member, which is attached to the substrate, protrudes from the substrate tray holder. Additionally, a holder plate can be disposed vertically.
Also, to control and improve such conditions as a transferring speed and location of the substrate, to the transferring apparatus can sense an entrance and discharge of the substrate. Additionally, a transferring apparatus for transferring the upright tray, to which the glass substrate and the mask are attached, and a guide means for holding the tray vertically can be included.